In a letter to RT’s London Office, NatWest said: “We have recently undertaken a review of your banking arrangements with us and reached the conclusion that we will no longer provide these facilities.”

The bank also said the Royal Bank of Scotland Group, which NatWest is a part of, would refuse to serve Russia Today.

“We have no idea why it happened, because neither yesterday nor the day before yesterday, nor a month ago, nothing special happened to us, nobody threatened us in any way,” Margarita Simonyan told the RBK business news website.

“Hypothetically, this may have something to do with new British and American sanctions against Russia, which may be announced soon. It may not. Our legal department is dealing with the issue now.”

In a post on Facebook, Russian Foreign Ministry spokeswoman Maria Zakharova said: “Britain on its way out of the EU abandoned all its commitments to protect the freedom of speech.”

She gave no information on why the accounts have been frozen, (or how much money had been stolen.)

A spokeswoman for Russia Today said: “RT has received a letter from Natwest, part of the Royal Bank of Scotland Group, which has a significant shareholding by the UK Government, informing it that its UK banking facilities with the bank will be withdrawn without explanation or redress.

“This decision is incomprehensible, and without warning.

“It is, however, not at odds with the countless measures that have been undertaken in the UK and Europe over the last few years to ostracize, shout down, or downright impede the work of RT.”

She added: “RT UK will continue its operations uninterrupted.”

RT, originally known as Russia Today, is a television network and news website funded by the Russian government.

It was previously sanctioned by Ofcom for biased or misleading reports on the conflicts in Ukraine and Syria.